首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   127106篇
  免费   10752篇
  国内免费   8182篇
耳鼻咽喉   1041篇
儿科学   1564篇
妇产科学   2327篇
基础医学   14880篇
口腔科学   2083篇
临床医学   16530篇
内科学   20756篇
皮肤病学   1455篇
神经病学   6931篇
特种医学   4340篇
外国民族医学   70篇
外科学   13215篇
综合类   19097篇
现状与发展   24篇
一般理论   5篇
预防医学   7867篇
眼科学   3663篇
药学   12881篇
  118篇
中国医学   6093篇
肿瘤学   11100篇
  2024年   349篇
  2023年   1838篇
  2022年   4704篇
  2021年   5935篇
  2020年   4261篇
  2019年   4106篇
  2018年   4155篇
  2017年   3705篇
  2016年   3470篇
  2015年   5241篇
  2014年   6574篇
  2013年   6136篇
  2012年   8958篇
  2011年   9816篇
  2010年   5992篇
  2009年   4764篇
  2008年   6546篇
  2007年   6539篇
  2006年   6611篇
  2005年   6522篇
  2004年   4494篇
  2003年   4251篇
  2002年   3609篇
  2001年   3251篇
  2000年   3343篇
  1999年   3480篇
  1998年   2254篇
  1997年   2181篇
  1996年   1571篇
  1995年   1462篇
  1994年   1278篇
  1993年   821篇
  1992年   1230篇
  1991年   1078篇
  1990年   934篇
  1989年   824篇
  1988年   713篇
  1987年   668篇
  1986年   508篇
  1985年   464篇
  1984年   249篇
  1983年   178篇
  1982年   118篇
  1981年   116篇
  1980年   76篇
  1979年   120篇
  1978年   59篇
  1976年   52篇
  1975年   55篇
  1974年   65篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
四叠体池蛛网膜囊肿   总被引:2,自引:0,他引:2  
目的:探讨四叠体池蛛网膜囊肿的临床特征和治疗方法。方法:对11例四叠体池蛛网膜囊肿进行了回顾性总结分析。所采用的手术方法有:①脑室分流手术;②囊肿-腹腔分流术;③囊肿切除;④囊肿切除加囊肿-脑池分流术,或囊肿部分切除(即囊肿开窗术),或囊肿切除加脑室-脑池分流术。结果:其主要临床表现以颅内压增高症和中线综合征为主。上述方法中单纯囊肿壁切除只能使部分病人的病情缓解,脑室分流或囊肿切除加脑室分流手术的疗效较好。结论:四叠体区蛛网膜囊肿常合并梗阻性脑积水,单纯囊肿切除不能解除多数病人的梗阻性脑积水。作者根据囊肿是否与蛛网膜下腔相通提出:对交通性蛛网膜囊肿采用单纯性脑室分流术,对非交通性者采用囊肿切除加脑室分流手术的治疗方法。  相似文献   
23.
Objective: To examine the relationship between ambient lead levels and blood lead levels and to explore the modifiers of the relationship between ambient lead and blood lead. Method: A cross-sectional study was conducted in two lead battery factories. Blood lead level and ambient lead concentration were measured for each participant concurrently. A structured questionnaire was administered to collect sociodemographic characteristics and occupational history. Design: Biological and personal environmental measurements of 219 lead-exposed workers were analyzed by both simple and multiple linear regression. A regression model was selected for interpretation. Results: A high correlation (r=0.62) between ambient lead (PbA) and blood lead (PbB) was observed. In addition, numerous factors, including age, sex, alcohol consumption, personal hygiene practice and type of lead exposure, were also found to influence blood lead levels. Although PbB was highly correlated with PbA, blood lead level may not be effectively lowered by reducing ambient lead level. Based on the regression coefficients, improvement of hygienic practice was more effective at lowering PbB than reducing ambient lead level. Good hygienic practice may be the preferential way to reduce lead exposure in current conditions. Conclusion: Education of correct work practice may be more important than engineering control in the developing countries to lower blood lead levels in lead battery factories. Received: 28 May 1996/Accepted: 30 August 1996  相似文献   
24.
The hereditary characteristics of enzyme deficiency and dermatoglyphics in congenital color blindness (CCB) were studied. We propose that there is a linkage between the two loci on the X-chromosome determining CCB and glucose-6-phosphate dehydrogenase (G6PD), based on our study of a high incidence of G6PD deficiency in 156 male cases with CCB. The CCB gene is closely linked with that of G6PD deficiency from our pedigree investigations. The rise in the frequency of eight or more whorls, the low value of atd angle and the presenting rate of real palmar patterns of the thenar, hypothenar and I, areas presented the hereditary traits of congenital color blindness.  相似文献   
25.
The visual pursuit test is a method that collects and analyzes the characteristics of pursuit eye movements and examines the function of the eye movement system. This paper analyzes the model parameters of the smooth pursuit eye movement system in order to explore a method for improving the analysis. The input-output relationship of the smooth pursuit system can be expressed by a quasilinear model. We compute the model parameters (gain, phase, spectral purity, cross covariance) by digital signal processing. Eye movement is recorded by electrooculogram. Both eyes are tested individually. The visual target moves at frequencies of 0.2, 0.4, 0.8, 1.2, and 1.6 Hz. Ranges are gain, 1.01 to 0.70; phase, -0.1 ° to -66 °; spectral purity, 0.97 to 0.70; and cross covariance, 0.99 to 0.26. We tested 40 normal subjects as well as patients with ataxia (8), vertigo (18), and ophthalmoplegia (9). The oculomotor system of normal subjects functions as a linear system in the performance of this test at 0.2 to 0.8 Hz. The spectral purity dropped to about 0.70 at 1.6 Hz. The variability of all measures increases greatly at 1.6 Hz, which indicates that this target motion exceeds the tracking ability of many normal subjects and that the oculomotor system of normal subjects functions as a nonlinear system in this condition. Statistical tests show no significant differences between sex, age, and the two eyes. The model parameters tentatively proved effective in clinical application.  相似文献   
26.
本文在分析黑龙江省妇幼保健机构设置现状的基础上,论述了在社会主义市场经济新形势下,妇幼保健机构发展的指导思想、模式与对策。  相似文献   
27.
T Wu 《中华医学杂志》1990,70(2):72-6, 6
At extreme altitude of 5,620 m, cardiac function was examined with electrical impedance at rest and during exercise. Mountaineers as subjects of experiment were divided into two groups: 15 subjects were Tibetan natives, and 10 subjects were Han visitors of expedition (both were young healthy males). The results showed that no significant difference was seen between the two groups in cardiac pump function at rest. In the Han visitors during exercise, HR increase was restricted, SV and CO were decreased, and PEP/LVET ratio was increased. In the Tibetan natives, HR increased gradually with increased work load, SV tended to be stable CO increased significantly under higher work load, and PEP/LVET ratio decreased gradually. These results suggest that the Tibetan natives were adapted to hypoxic environment much better than the immigrants because their cardiac reserve capacity and maximal oxygen uptake were better than the immigrants at extreme altitude.  相似文献   
28.
29.
30.
OBJECTIVES: 1) To assess, with a peripheral magnetic resonance imaging system (pMRI), the prevalence of bony and soft tissue abnormalities in the knee joints of normal subjects, osteoarthritis (OA) patients, and individuals who have suffered an anterior cruciate ligament (ACL) rupture; and 2) to compare the prevalence among groups. METHODS: Magnetic resonance (MR) images of 28 healthy, 32 OA, and 26 ACL damaged knees were acquired with a 1.0-T pMRI system. Two radiologists graded the presence and severity of 9 MR image features: cartilage degeneration, osteophytes, subchondral cyst, bone marrow edema, meniscal abnormality, ligament integrity, loose bodies, popliteal cysts, and joint effusion. RESULTS: Ten of 28 healthy (35.7%), 24 of 26 ACL (92.3%), and all OA knees (100%) showed prevalent cartilage defects; 5 healthy (17.9%), 20 ACL (76.9%), and all OA knees (100%) had osteophytes; and 9 normal (32.1%), 21 ACL (80.8%), and 29 OA knees (90.6%) had meniscal abnormalities. One-half of the knees in the OA group (16 of 32, 50%) had subchondral cysts, and almost one-half had bone marrow edema (15 of 32, 46.9%). These features were not common in the ACL group (7.7%, and 11.5%, respectively) and were not observed in healthy knees. The OA group had the most severe cartilage defects, osteophytes, bone marrow edema, subchondral cysts, and meniscal abnormalities; the ACL group showed more severe cartilage defects, osteophytes, and meniscal abnormalities than did normal subjects. CONCLUSION: The results suggest that knees that have sustained ACL damage have OA-like reatures; most subjects (19 of 26, 73.1%) could be identified as in the early stage of OA. The prominent abnormalities present in ACL-damaged knees are cartilage defects, osteophytes, and meniscal abnormalities.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号